If Lauren pilots are on the BA seniority list, the jobs will inevitably go to the guys who are already on that list because they will have nothing to lose by going there.
I would be amazed if, behind closed doors, the BA CC want to see anyone other than BA pilots flying in Lauren. Why would they?
I see from today's Flight that the BA pilots are worried that the employment of non-BA pilots will involve the recruitment of inexperienced pilots, "putting the BA brand at risk". So to avoid that, let's get a bunch of BA senior first officers who've vegetated in the RHS for far too long and pop them straight into the LHS. Much safer.